We recently blogged on how alcoholics, and children of alcoholics, have difficulty with recognizing and differentiating external signs of emotions such as facial emotional expressions, now we will consider increasing evidence that alcoholics have difficulties with identifying and differentiating internal emotional states also.
Both these areas of research point to real difficulties in alcoholics in relation to the processing of emotion.
As we shall explain below, this deficit in emotional processing has real consequence for decision making capabilities and this has an important role to play in the initiation and maintenance of substance abuse and eventual addiction.
Alexythymia and Addiction
Effective emotion regulation skills include the ability to be aware of emotions, identify and label emotions, correctly interpret emotion-related bodily sensations, and accept and tolerate negative emotions (2,3).
Alexithymia is characterized by difficulties identifying, differentiating and expressing feelings. The prevalence rate of alexithymia in alcohol use disorders is between 45 to 67% (4,5)
Finn, Martin and Pihl (1987) investigated the presence of alexithymia among males at varying levels of genetic risk for alcoholism. They found that the high risk for alcoholism group was more likely to be alexithymic than the moderate and low genetic risk groups (6).
Higher scores on alexithymia were associated poorer emotion regulation skills, fewer percent days abstinent, greater alcohol dependence severity (7). Some studies have emphasized a right hemisphere deficit in alexithymia [8,9] based on the hypothesis that right hemisphere plays a more important role in emotion processing than the left [10, 11].
Dysfunction of the anterior cingulate cortex has been frequently argued, e.g., , and others have focused on neural substrates, such as the amygdala, insula, and orbitofrontal cortex (see the review in ). All different components of the the emotional regulation network.
These models may interact with each other and also map onto the brain region morphological vulnerability mentioned as being prevalent in alcoholics.
Magnetic resonance imaging and post-mortem neuropathological studies of alcoholics indicate that the greatest cortical loss occurs in the frontal lobes, with concurrent thinning of the corpus callosum. Additional damage has been documented for the amygdala and hippocampus, as well as in the white matter of the cerebellum. All of the critical areas of alcoholism-related brain damage are important for normal emotional functioning (14) .
One might speculate that thinning of the corpus collosum may render alcoholics less able to inhibit negative affect in right hemisphere circuits.
Alcoholics are thus vulnerable to thinning of the corpus collosum and perhaps even to emotional processing difficulties (15 ). The inability to identify and describe affective and physiological experiences is itself associated with the elevated negative affect (16) commonly seen in alcoholics, even in recovery (17.
Thus, this unpleasant experience might prompt individuals to engage in maladaptive behaviors, such as excessive alcohol consumption, in an effort to regulate emotions, or, more specifically, cope with negative emotional states (18 )
One neuroimaging study (19) looked at and compared various models of alexithymia showing people with alexithymia showed reduced activation in the dorsal ACC and right anterior insula (AI), and suggested individuals who exhibit impaired recognition of their own emotional states may be due to a dysfunction of the ACC-AI network, given these regions’ important role in self-awareness. These studies suggest alexithymics may not be able to use feelings to guide their behaviour appropriately.
The Iowa gambling task (IGT) was developed to assess decision-making processes based on emotion-guided evaluation. When alexithymics perform the IGT, they fail to learn an advantageous decision-making strategy and show reduced activity in the medial prefrontal cortex, a key area for successful performance of the IGT, and increased activity in the caudate, a region associated with impulsive choice (20).
The neural machinery in alexithymia is therefore activated more on the physiologic, motor-expressive level, similar to the study on children of alcoholics and thus may represent a vulnerability.
The function of the caudate is to regulate or control impulsivity and disinhibition. Individuals with alexithymia may work on the IGT impulsively rather than by using emotion-based signals. This IGT study suggests that individuals with alexithymia may be unable to use feelings to guide their behavior appropriately.
Alexithymic individuals thus may be unable to use emotion for flexible cognitive regulation. Thus, there may be dysfunction in the interaction of the aspects of the emotional response system in alexithymia with greater activation in the caudate (basal ganglia) and less activation in the mPFC in alexithymics during the IGT.
Thus alexithymics show weak responses in structures necessary for the representation of emotion used in conscious cognition and stronger responses at levels focused on action. This ties in with the blog on an emotional disease? and also so how is your decision making? which suggested that alcoholics do not use emotion to guide decision making and rely on more motor, or automatic/compulsive parts of the brain to make decisions.
Consequently, alexithymics experience inflexible cognitive regulation, owing to impairment of the emotion guiding system. These dysregulated physiological responses over many years may result in untoward health effects such as drug addiction.
To illustrate this, one study demonstrated that patients with cocaine dependence had higher alexithymia scores compared with healthy control subjects (21).
In a study of 46 inpatients with alcohol abuse or dependence, the total TAS (Toronto Alexithymia Scale) score was significantly higher among those who relapsed after discharge than among those who did not, even when depressive symptoms were taken into account(4)
Cocaine-dependent patients also failed to activate the anterior cingulate and other paralimbic regions during stress imagery, suggesting dysregulation of control under emotional distress in these patients (22).
Instead, cocaine-dependent patients demonstrated greater craving-related activation in the dorsal striatum, a region that has been implicated in reward processing and obsessive–compulsive behaviours. The greater activation associated with alexithymia in men in the right putamen during stress is broadly consistent with earlier studies implicating the striatum in emotional motor responses.
This also corresponds to the study of children of alcoholics show significantly more activation in the left dorsal anterior cingulate cortex and left caudate nucleus a region associated with impulsive choice, illustrating perhaps in children of alcoholics a bias in brain decision-making systems as an underlying elevated risk for alcoholism.
We have also suggested previously a ‘compulsive’ emotional habit bias in endpoint addiction which reflects a stiumulus response or automatic behaviour in the face of emotional distress, which then influences an automatic decision making profile. This may be the effect of chronic drug use impacting on an inherited emotional expressive-motor decision making vulnerability seen in children of alcoholics.
In simple terms, these vulnerable individuals may recruit more automatic rather than goal-directed areas of the brain when making decisions. This would result in impulsive/compulsive decisions which do not fully consider consequences, negative or otherwise, of their decisions and resultant actions. This decision making profile would then have obvious consequences in terms of a propensity to addiction.
References (to be finished)
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